====== a. Shell and CDO =======

Shown below is an example that interpolates one data file from the dpp0016 simulation onto a regular 1°x°1 global grid.

For the interpolation example shown here, a grid description text-file and a weight netcdf-file are needed.

The grid description text-file for an intented 1°x°1 globally grid is as follows:

    # gridID 1
    #
    gridtype  = lonlat
    gridsize  = 64800
    xsize     = 360
    ysize     = 180
    xname     = lon
    xlongname = "longitude"
    xunits    = "degrees_east"
    yname     = lat
    ylongname = "latitude"
    yunits    = "degrees_north"
    xfirst    = -179.5
    xinc      = 1
    yfirst    = -89.5
    yinc      = 1 

Simply create a text file with any text editor, copy and paste the text above into the file and name the file, for example, "griddes_1x1.txt". It can be convenient to do this only once and keep it for later multiple applications in the users ''$HOME'' or ''$WORK''-directory. If the intended grid should be of a different resolution, say 0.1°x0.1°, then the grid discription would be :

    # gridID 1
    #
    gridtype  = lonlat
    gridsize  = 6480000
    xsize     = 3600
    ysize     = 1800
    xname     = lon
    xlongname = "longitude"
    xunits    = "degrees_east"
    yname     = lat
    ylongname = "latitude"
    yunits    = "degrees_north"
    xfirst    = -179.95
    xinc      = 0.1
    yfirst    = -89.95
    yinc      = 0.1 

The weight file can be created using CDO. For this you need the grid description text-file shown above, the ICON grid-file for the native model grid (in this case R2B9 for the dpp0016 simulation) and also one dpp0016 data file is required. The ICON grid-file of the dpp0016 simulation can be found at /pool/data/ICON/grids/public/mpim/0015/icon_grid_0015_R02B09_G.nc. The general structure of the CDO command creating the weight file is:

<code bash>
cdo gendis,grid-description-text-file -setgrid,ICON_grid_file one_dpp0016_data weightfile
</code>

For example, storing the output weight file to the ''$SCRATCH''-directory:

<code bash>
cdo gendis,griddes_1x1.txt -setgrid,/pool/data/ICON/grids/public/mpim/0015/icon_grid_0015_R02B09_G.nc /work/mh0287/k203123/GIT/icon-aes-dyw_albW/experiments/dpp0016/dpp0016_atm_2d_ml_20200201T000000Z.nc $SCRATCH/weight_dpp0016_1x1.nc
</code>

Now, the interpolation can be done via:

<code bash>
cdo -remap,griddes_1x1.txt,$SCRATCH/weight_dpp0016_1x1.nc /work/mh0287/k203123/GIT/icon-aes-dyw_albW/experiments/dpp0016/dpp0016_atm_2d_ml_20200201T000000Z.nc $SCRATCH/dpp0016_atm_2d_ml_20200201T000000Z_1x1.nc 
</code>